The invention relates to a device to detect various states such as deformation states, movements and loading states of a component, having a transmitter and a receiver that are arranged independently and at a distance from each other on at least one component, and the invention also relates to an evaluation unit.
A transducer of deformation states of a component is already known from U.S. Pat. No. 5,170,366. This transducer emits acoustic signals by means of a transmitter provided in or on the component and it receives acoustic signals with a receiver arranged on or in another place on the component. The various loading states of the component such as, for example, deformation due to stretching, compression or torsion result in various delay time differences of the acoustic signals. In the case of stretching of the component, the propagation rate decreases while in the case of a compression, the propagation rate of the acoustic signals increases. In order to obtain a correlation between the measured delay times and the component load, it is necessary to determine the possible loading states and thus the various delay times between the transmitter and the receiver in a simulation phase. Moreover, it is necessary to equalize and evaluate all of the parameters that have an influence on the propagation rate and that cannot be ascribed to a loading of the component such as, for instance, the temperature or fault signals.
U.S. Pat. No. 3,708,231 shows a device to detect angular changes of a component, whereby the reflection behavior of a light beam on a slanted, plane surface is evaluated. Component deformations such as, for example, bending, cannot be detected with this arrangement. French Patent No. 2,578,974 relates to a device to determine a force or the movement resulting from said force. Here, inside a flexible housing, there is a light transmitter and, opposite from it in the housing, an optical receiver. Due to the optical property or characteristic of the light that propagates in the housing, a deformation of the housing can be detected. A small, dynamic relative movement between the transmitter and the receiver cannot be detected with such a device.
The invention is based on the objective of creating and configuring a deformation transducer in such a way that a rapid and simple determination of various loading states of the component is possible.
This objective is achieved according to the invention in that the transmitter emits a focused or punctiform electromagnetic wave or a focused acoustic wave or a focused particle beam outside of the component towards the receiver. The result of this is that the transmitter and the receiver are effectively linked to each other via the light beam so that, for example, deformations of the component have an effect on the relative position between the transmitter and the receiver and thus also on the path of the light beam relative to the receiver. This device is suitable as a weighing device since the deformation of a component allows a conclusion to be drawn about the force acting upon it. However, other influencing variables that entail a deformation of the component such as, for example, dynamic loads or an unbalance, can also be ascertained. For such a position determination, it is also conceivable to use a pressure wave or sound wave or else a water jet.
In this context, it is also advantageous for the transmitter and the receiver to each be arranged in a holder on the component in such a way that a deformation of the component is equivalent to the position shift of the electromagnetic wave or of the light beam on the receiver. Thus, every deformation of the component leads to a change in the light beam path relative to the receiver. This change serves to determine the component deformation or the component oscillation or else it is equivalent thereto. This also offers the possibilityxe2x80x94via the deformation state of the componentxe2x80x94to detect the force that causes the deformation; that is to say, for example, the weight of a load like that of a train on a railway track that is deformed under its load can be determined. The dynamic weighing of a train is also an option.
According to an embodiment, an additional possibility is that, within the beam path of the light beam, there is at least one reflector or one reflective surface and that the light beam is reflected by the reflector or by the reflective surface towards the receiver, whereby the reflector is connected to the component via a holder. For this purpose, it is also advantageous for the transmitter and the receiver to be arranged on a shared side of the housing opposite from the reflector or from the reflective surface. Therefore, the beam path of the light beam is lengthened two-fold, four-fold or multiple-fold depending on the number of reflectors. Thus, the deviation of the light beam resulting from the component deformation is increased by this lengthening factor, which leads to a considerable resolution of the component deformation. Consequently, any slight deformation can be resolved and determined. The arrangement of the reflector on the component has the advantage that the transmitter-receiver unit in its entirety is arranged on the component by means of a separate holder.
Finally, according to a preferred embodiment of the solution according to the invention, it is provided that the receiver has a light-sensitive surface such as a PSD transducer or an image processing element and the light-sensitive surface ensures a resolution of at least 3000 d to 6000 d. This value, which is common in weighing technology, is determined from the quotient of the length ratios of the maximum measurable deviation of the light beam to the light-sensitive surface and the diameter of the smallest optical unit. In this manner, the deviations of the reflected light beam relative to its starting position and thus the component deformation can be determined on the basis of the above-mentioned resolution. Here, it must be noted that the deviation of the light beam is already enlarged by the corresponding factor due to the multiple reflection of the beam path.
An especially important aspect for the present invention is that the transmitter should emit at least one light beam such as a laser beam. Thus, it is also possible that the component deformation can be evaluated by means of two or three light beams whose frequency and/or position differ. The use of a laser beam is extremely advantageous in terms of the scatter or the position detection. The use of another medium such as, for example, water, for generating a beam path is also conceivable.
In conjunction with the design and arrangement according to the invention, it is advantageous for the transmitter, the receiver and the reflector to be arranged in a flexible housing. The housing serves to protect the beam path from external influences. By designing the housing so as to be flexible, it is possible to prevent the relative movements between the various elements due to component deformation.
Regarding the beam path lengthening, it is advantageous for at least one semi-transparent layer to be arranged inside the beam path leading from the transmitter to the receiver. In this manner, one part of the intensity of the emitted light beam is reflected and the other part of the intensity of the beam path continues further. Thus, a position image of the beam path on the receiver is obtained which indicates various resolution stages of the component deformation corresponding to the number of reflections.
For this purpose, it is also advantageous for the transmitter and/or the receiver and/or the housing to be round or rectangular in shape. Depending on the potential component deformation or on the area of application, an optimal utilization of the available surfaces can be achieved in this manner. The round housing shape serves essentially for the use of the transducer in the form of a drill core or as a drill core substitute. This core is inserted into a bore or received by it in order to determine the component deformations there. Thus, the transducer can be used, for instance, in a foundation in order to determine the deformations or oscillations present there.
It is also advantageous for the receiver or the PSD transducer to be associated with an evaluation logic circuit in order to determine the deformation of the component. The component deformation manifested by the deviation of the reflected light is determined by means of an evaluation logic circuit. Consequently, the transducer can also be employed as a weighing member.
In conjunction with the design and arrangement according to the invention, it is advantageous for the transmitter and the receiver to be arranged together on a plate that is clamped to a component by means of at least one clamping element, whereby the clamping element has two pointed or round contact parts and at least one bore that matches the plate. Via these bores, the clamping element is put into contact, on the one hand, with the plate and, on the other hand, with the railway track, so that the deformations of the component are transmitted to the transmitter and to the receiver. The resultant contact surface is linear here, as a result of which a non-redundant support is achieved. This avoids the need for complicated drilling or gluing to the component.
Finally, it is advantageous for the transmitter and the receiverxe2x80x94together in one holderxe2x80x94and for the reflectorxe2x80x94independent of and at a distance from them in another holderxe2x80x94to be arranged on the component in a shared housing.